Pump



Sept. 17, 1935. D. MITCHELL. JR 2,014,860 PUMP Filed May 221954 S SheetS-Simet 1 D. MITCHELL. JR

PUMP

Sept. 17, 1935.

Filed May 22, 1934 5 Sheets-Sheet 2 GUM/M411 4 Sept. 17, 1935. i D, MITCHELL. JR 2,

' PUMP Filed May 22, 1934 5 Sheets-Sheet 3 Sept. 17, 1935. NHTCHELL, JR 2,014,860

PUMP

Filed May 22, 19:54 5 Sheets Sheet 4 95 61 1 E 86 a: 1 l l 94. \\\\\\1 I m Y W Sept. 17, 1935. D. MITCHELL. JR

PUMP

5 Sheets-Sheet 5 Filed May 22, 1934 Patented Sept. 17, 1935 UNITED "STATES PATENT" OFFICE rpm mm Mitchell, In, Buena Park, can. Application May zz, 1934-, Serial R0. was SClaiml. (01. 103-182) Thisinvention relates to pumps and particularly to multicylinder pumpsof the type in which the cylinders are positioned parallel to each other and disposed symmetrically about a common central' axis, and the plungers reciprocated by a wobble plate pivotally supported at the common axis. A useful characteristic of such pumps is that by varying the arc of movement of the wobble plate the strokes of the pump plungers may be varied'to any desired extent between zero and maximum.

An object of the invention is to simplify the construction and improve the efliciency of pumps of the type described.

v Another object is to provide a construction for pumps of the general type described in which the pump barrels and plungers are readily removable from the rest of the mechanism and in which barrel and plunger" assemblies of different sizes may be interchanged without disturbing the operating mechanism of the pump.

Another object is to provide a pump of the general type referred to that automatically varies its stroke as necessary to maintain a predetermined pressure and in which the predetermined pressure may be varied while the pump is operating.

A further object is to provide apump for automatically maintaining a predetermined pressure in the discharge line without utilizing the fluid in the discharge line to actuate the pressurecont'rol mechanism, thereby completely segregating the working suction and discharge lines of the pump from the control mechanism.

Other more specific objects. and features of the invention will be apparent from the following detailed description which refers to the drawmgs.

In the drawings:

Fig. 1 is a vertical section of a complete pump in accordance with the invention;

Fig. 2 is a horizontal section'in the plane II-II of Fig. 1;

Fig. 3. is a horizontal section in the plane III-III of Fig. 1;

' Fig; 4 is a horizontal section in the plane IV--IV of Fig. l;

Fig. 5 is a vertical detail section through the main rotor member "of the pump in the plane V-V of Fig. 3;

Fig. 6 is a detail longitudinal vertical sectiona pump which is a modification of that in Fig. 1, the construction of-the portion not shown corresponding to the construction shown in Fig. 1 and the section being taken in the plane VII-VII of Figs. 8 and 9;

Fig. 8 is a horizontal section in the plane 5 VIII--VIIIofFig.7; and Y a Fig. -9 is a horizontal section, in the .plane IXIX of Fig. 7. l

Referring first to Figs. 1 to 6 of the drawings, the pump therein disclosed comprises an outer 10 casing I, within which substantially the entire mechanism is contained. This case i is preferably made in three sections, there being an upper section 2, a middle section 3 and a lower section I. The upper and lower sections constitute closed 15 ends for the casing and are provided with flanges cooperating with flanges on the middle section 3 for securing the sections together. Thus they are preferably united by bolts 5 which pass through the flanges on the lower and middle sec- 2 tions and screw into threaded apertures in the flange on the upper section.

The pump mechanism properv is contained within the middle and lower sections of the case.

Thus the middle section 3 has secured therein 2 x as by screws ii a hollow cylindrical block I in which openings constituting barrels and valve v chambers are formed. The shape of one of the barrels and its associated valve chamber is clearly shown in Fig. 1, the barrel being indicated at 30 8 and the valve chamber at 9; It will be observed that each valve chamber 9 is divided into two compartments, the lower compartment Ill having an inlet opening ll extending upwardly therein from the interior of the pump casing with a ball 35 valve l2 for closing the opening during the comprssion stroke of the pump and the upper portion i3 communicating with the lower portion Ill through a passage ll adapted to be. closed by a ball valve it during the suction stroke of the 4 pump. The upper chamber l3 also connects with a discharge passage I 6 (Fig. 4) which connects to one or the other of two discharge manifolds l1 and I8, respectively. Two discharge manifolds are employed for the reason that part of .4 the barrel and valve assemblies constitute the working portion of the pump for supplyin fluid under pressure to a working line and the remaining pump and barrel assemblies constitute control pumps for automatically regulating the 50 pressure developed'by the pump. In the particular pump shown there are nine working barrels and three control barrels.

Referring for the moment to Fig. 4, the nine working barrels identified by the reference .uu- 55 meral it are symmetrically spaced circumferentially from each other about the center axis of the casingv and have their associated discharge passages l6 connected through passages 26 to the main discharge manifold H, which is connected to a discharge orifice 2| in the exterior of the pump casing. The control barrels 22, three in number, are also symmetrically spaced circumferentially about the axis of the casing, each being located between a .pair of working barrels IS. The discharge passages l6 from the valves of the control barrels 22 connect directly to the discharge manifold l6, which in turn is connected to a discharge pipe 24 (Fig. 1) which extends upwardly through the casing and out through the top ofthe casing, at which point it connectswith the pressure control mechanism for automatically controlling the pump. As previously stated,

all of the inlet passages H on both the working and controlling pump assemblies communicate with the interior of the pump casing which is adapted to be kept partially fllled with the fluid to be pumped. The pump is particularly designed for supplying fluid such as oil to a hydraulic press or the like and-in this, case the 011 within the casing serves to lubricate the pump.

Each pump barrel 8 (the reference numeral 8 being generic to both the control and working barrels) is provided with a. plunger 25, which is preferably equipped with packing cups 26 at its upper end and the lower end of which extends out of the barrel. Each plunger is reciprocated by a wobble plate 21 which comprises a disc projecting into the axes of the various plungers 25. Thus each plunger is provided in its lower end with a ball 26 which bears against the'upper face of the plate 21. Each plunger is also connected by a yoke 29 which extends around the edge ,of the plate 21 with a guide plunger 36 adapted to reciprocate in a guide bushing 3| mounted in the-lower casing member 4. Each guide plunger 30 is drilled to receive a detent 32 which is maintained in engagement with the under-side of the plate 21 by a spring 33. The lower end of the plunger guide 3| opens into a cavity 34 provided in the lower casing member 4, which cavity communicates through passages 35 with the interior of the casing to permit free surging of oil into and .out of the guides II as 'the plungers 36 reciprocate.

The plate 21 is rigidly secured to and forms a part of a spindle 66 which is pivotally mounted extension 36 and a nut 36.

for rocking movement on a ball 31 rigidly secured to the lower case member 4 by a threaded The spindle 36 is provided with a socket in its under side to smoothly engage the ball 31 and the spindle is secured in position upon the ball by a cap-46 threaded into the under side of the spindle. In operation the upper end of the spindle 36 gyrates about a central vertical axis passing through the ball 61, the arc of gyration being variable and determining the strokes of the plungers 25.

' To gyrate the spindle 36 a rotor element 4| is provided in the upper end of the pump casing, this rotor element being rotatably supported in the pump casing between a lower tapered roller bearing 42 and an upper tapered roller bearing 43. Thus the lower end'of member 4i is provided with a cylindrical shoulder 44, upon which there is mounted a cone 45 and the inner wall of the central casimr, member 3 is provided with a shoulder 46 upon which rests a bearing cup 41, rollers 48 being positioned between the cup and cone. The upper bearing assembly 46 comprises a cone 4 means of adjusting bolts 54, preferably three in number, which are threaded into the upper case member and contact a ring 55 which bears against the upper end of the cup The memher 4| is adapted to be rotated through a beveled gear 56 mounted thereon which meshes with a drive pinion 51 mounted on a shaft 58 journaled in a bearing 59 in the wall of the casing member.

A pulley 60 is shown mounted on the outer end vof the shaft 58 although it is to be understood that if desired this shaft may be coupled directly to an electric motor or other source of power. The upper end of the spindle 36 is engaged between a pair of parallel guide faces in the rotating member 4!, these guide faces being indicated at Si in Fig. 3. To permit free rotation of the member 4| without undue friction between the upper end of the spindle and the guide faces 6!, a sleeve 62 is mounted upon the upper end of the spindle 36 and separated therefrom by ball bearings 63.

It will be observed from inspection of Figs. 1 and 3 that the sleeve 62 on the upper end of spindle 36 is freely movable in a radial direction with respect to the vertical axis through the ball 31. between the guide faces 6i and, by shifting the upper end of the spindle outwardly from the axis or inwardly toward the axis, the effective stroke of the pump plungers 25 may be varied from zero to maximum value. The reaction of the pump plungers 25 tends to restore the spindle 36 to central position. Therefore in order to reciprocate the plungers the spindle 36 must be maintained in off center position by some force.

This force is provided in the present pump by hydraulic means. Thus (referring to Fig. 5) there are provided in the upper part of the, rotatable member 4l a pair of cylinders 64 positioned on opposite sides of and parallel to the guideway defined between the guide surfaces 6i, the main portions of these cylinders being positioned to the right of the center line of the member 4! as it is shown in Fig. 1. These cylinders 64 are provided with ports 65 (Fig. 3) in their forward ends for the admission of fluid under pressure and contain plungers 66 of substantial length which are preferably provided with packing cups 61 on their forward ends. The plungers 66 are drilled adjacent their rear ends to receive stub shafts 66 on a yoke 69 which is curved to engage the sleeve 62 on the upper end ofspindle 36. The rear ends of the walls of the cylinders 64 are provided with longitudinal slots 6la communicating with the guideway in which the sleeve 62 is positioned to permit longitudinal movement of the yoke 66 and plungers 66. It will be observed that with the construction described the spindle 36 may be shifted of! center by applying fluid pressure to the cylinders 64 through their ports 65 and that the radial position of the spindle 36 with respect to the neutral axis will be determined by the relative values of the reactive forces acting on i the pump plungers 25 and the pressure of the fluid in the control cylinders 64.

v Since the member 4i containing the control cylinders 6.4 is constantly rotating when the pump is in operation, special means must be provided to introduce pressure fluid for control purposes to the cylinder 64.-- This pressure fluid is introduced, in the embodiment shown, through a packing joint located in the upper end of the pump casing. Thus the ports 88 (Fig. 3) com- 'municate with a passage 18 which is connected fitting 18 secured to .the case by cap screws 11 and containing a packing 18 which is adapted to be compressed by a packing nut 18 to form a fluid seal between the nipple 12 and the sleeve 18. Although pressure fluid from any desired source may be supplied to the controlcylinders, 88, I

prefer to supply this fluid from the three control barrels 22 of the pump and to this end the dis- 1 charge tube 28, which extends through the upper wall of the pump casing, is connected into the fitting 18 which, as previously described, is ,con-

nected to the control cylinders 84.

If the output from the control barrels 22 of the pump were connected directly through a closed system to the control cylinders 84, a terriflc pressure would be built up. and applied to the plungers 88 which would maintain the spindie 38 in maximum -oil? center position regardless of the reaction of the various pump plungers 28. It is therefore necessary to regulate the pressure applied to the control cylinders 88 and I effect this regulation by means of a relief valve which is indicated generally at 88 in Fig. v1 and is shown in detail in Figs. 2 and 3.

The relief valve proper is removable as a unit.

82 andthe inner end constitutes a closed hollow cap 88 which communicates through a passage 88 (Fig. 1) with the interior of the fitting 18. This-passage 84 is also.shown in the vertical sectional view of Fig. 6. The inner end of the tubular member 8| and the outer end of the cap 88 are threaded so that the parts screw together to form a fluid tight seal. A valve seat 88 is threaded into the inner end of the tubular member 8| and cooperates with a valve ball 88 which is pressed against the seat 88 by a plunger 81 which in turn is forced against the ball with a predetermined pressure by a coil spring 88 which is interposed between the plunger 81 and a retainer 88. The retainer 88 is provided with'outwardly extending ears 80 on opposite sides thereof which slide in longitudinal slots 8| provided in the tubular member 8|. The retainer 88 is provided with a threaded aperture in the center which screws onto a threaded adjusting shaft 82 rotatably supported in a plug 88 threaded into the outer end of the tubular member 8|. Shaft 82 projects through and beyond the plug 88 and is provided with a squared end 84 so that it can be, turned with a wrench. The shaft 82 is provided with a shoulder 88 interior of the plug 83, which shoulder bears against the plug and prevents the shaft 82 moving outwardly in response to the pressure exerted by the spring 88. It will be observed that by turning the shaft 82 the spring retainer 88 may be shifted longitudinally in the tubular the valve ball at between wide limits. The presthe valve ball 88 away from its seat whenever the pressure exceeds the predetermined value for which the valve is adjusted, thereby discharging fluid past the valve ball and out through a dissure fluid delivered through the passage 88 shifts casing where it returns to the fluid supply maintained in the casing.

Ifthe pump as described happened to be on dead center, that is, with the spindle 88 in alignstantly urged outwardly into the position shown in Fig. 1 by a spiral spring 88 positioned back thereof. It will be observed that the outer end of the plunger 81 is in the path of the sleeve 82 on the. upper end of spindle 38 so that whenever the spindle tends to move into central position it intercepts the plunger 81 and is resiliently urged away from the central position.

When the pump is in operation, the plungers 28 in both the working barrels l8 and the control barrels '22 are uniformly sequentially reciprocated to deliver fluid from the interior of the pump casing to the discharge manifolds l1 and I8. The fluid discharged to the manifold I1 is discharged to any suitable discharge line through the discharge port 2| (Fig. 4) and all of the fluid from manifold I8 is discharged through the pipe 28 to the control valve 88 and through fitting 18, pipe 18, nipple 12, passage 1| and passages 18 to the control cylinders 88 where it acts against the control plungers 88 tending to shift the latter to the left (with reference to Fig. 3) and thereby move the spindle 88 into maximum off center position (the position of maximum stroke). The spindle will terrain in this position so long as the back pressure in the main discharge line remains below a predetermined value, under-which conditions the pump operates with maximum volumetric emciency to deliver a full stream of fluid. In the meantime, the, fluid discharged from the control barrels 22 must all be discharged through the control valve 80 so that'a constant pressure of magnitude dependent upon the setting of the ders 88. However, should the back pressure in the main discharge line rise above a predetercontrol valve is maintained in the control cylin- Y mined value dependent upon the setting of the fective stroke of the pump. If the discharge line is not completely closed off, the reduction in the stroke of the pump will be just suflicient to maintain the predetermined pressure in the discharge line. However, if the discharge line should be completely closed off, then the reaction of the plungers 28 and working cylinders will be sufficient to force the spindle 88into its central position in which no pumping motion whatever oocurs. The spring tension on the plunger 31, which tends to maintain the spindle of! its dead center position, is insuflicient to maintain the spindle of! center when the reaction of the plungers 25 and the working cylinders rises appreciably above the predetermined pressure for which the pump is set. Should at any time the pressure in the discharge line be reduced, the

constant force exerted upon the spindle through the yoke 60 by the plungers 66 in the control cylinders 04 shifts the spindle ofl center to increase the amount of fluid pumped sufllcient to restore the pressure in the discharge line to the predetermined value or to permit the spindle to move spindle 36 and the supporting ball'3'l operates in the oil in the casing and therefore little frictional losses occur at this point. Furthermore, the motion between the ball 31 and the socket in the spindle 36 is relatively slight for the reason that the spindle 30 does not necessarily rotate (although it is free to do so) but merely rocks around the ball 31.

Although in the pump illustrated the working barrels I9 and the control barrels 22 are identical in construction and size, it is not essential that they be of the same size. As a matter of fact, since very litle fluid need be supplied to the control valve 30, the control barrels I9 and their plungers 25 may be of substantially smaller size than the working barrels I9 and their associated plungers, thereby reducing the reactive force of the control plungers upon the spindle 36 and increasing the efficiency of the pump.

As previously stated, the embodiment of the pump disclosed in- Figs. 1 to 6 is designed particularly for. supplying fluid such. as oil to a hydraulic press or the like. .In such a device the fluid from the press would be returned to the pump casing through any suitable connection, thereby maintaining a substantially constant supply of oil in the pump casing. However, there are many applications in which a fluid other than 011 is to be pumped and in which the pumped fluid is not necessarily circulated through a closed system. My pump can be readily adapted for such purposes by pomtioning the working barrels below the plate 21 (Fig. 1) and preferably attachable and removable as a separate unit from the rest of the mechanism. Such a unit is disclosedin Figs. 7, 8 and 9.

Fig. '7 discloses onlythe lower portion of a complete pump, the upper portion of the pump corresponding exactly to the upper portion of the pump shown in Fig. 1. Thus corresponding parts in the pump shown in Fig. l are identified by the same reference numerals employed in Fig. 1 with the sufllx It will be observed that the control barrels 22a, which may be three in number the same as in the pump shown in Fig. 1, are positioned above the wobble plate 21a I exactly the same as in Fig. 1 and the connections from these control barrels through their associated valves to the control valve (not shown in Fig. 7) are exactly the same as in Fig. 1.

The working barrels, however, are positioned in a separate casing unit I00, which bolts onto the bottom of the casing unit 411. The working barrels IOI and their associated suction and discharge valves I02 are substantially identical in construction to the corresponding construction shown in Fig. 1 except that they are inverted and the plungers I03 in the working barrels are connected by push rods I04 extending up through the bottom wall of the casing member 4a and contacting with the under side of the wobble plate 21a. The push rods I04 are connected by 'yokes I05 extending beyond the edge of the wobble plate 21a to guide rods I06 positioned thereabove and reciprocating in guides I01 mounted in the web I08 in the middle casing 3a. Spring controlled detents I09 are provided in the guides I06, which detents bear against the upper'end of the wobble plate 21a to positively link the push rods I04 with the wobble plate. Since the control barrels 22a of the pump shown in Fig. '7 pump oil exactly the same as in the model shown in Fig. 1, that portion of the pump casing including the sections 4a and 3a is adapted to be filled with oil. It is therefore necessary to pre- 25 vent leakage of the oil from the casing section 4a down into the pump casing I00. To this end, I

the push rods I04 are mounted in packing glands H0 and the lower ends of the bushings 3Ia in which the push rods a of the control 30 barrels reciprocate are closed at their lower ends by solid end walls III and longitudinal grooves II2 are provided in the surfaces of the bushings 3Ia to permit the oil to surge in and out below the guide rods 38 as the latter reciprocate. V The plungers I03 in the working barrels are preferably detachable from the push rods I04 and are therefore shown joined to the push rods by screw thread connections, as shown at II3. This construction permits the complete removal 40 of the block II 4 containing the working barrels IM and their associated valves, together with the plungers I03 and the substitution of a different block containing barrels of different diameter together with plungers to flt.

In the embodiment of Fig. 7, since the fluid connections to the working barrels are entirely separate and distinct from the pump casing containing the oil or other fluid used to actuate the control mechanism, the intake ports of the valves I02 are all connected to a common intake manifold II5 adapted to be connected to any desired source through a terminal connection H6 and the exhaust ports of the valves I02 are all connected to an exhaust manifold I I1 adapted to be connected to a discharge line.

The automatic operation of the pump disclosed in Fig. 7 is exactly the same as that of Fig. 1. The maximum pressure delivered by the pump is determined by thesetting of the control valve mechanism (which corresponds exactly to the mechanism shown in Fig. 1), which mechanism functions to decrease or increase the deflection of the spindle 36a with respect to the center line to vary the volume output of the pump. 5

Although the invention has been disclosed and described particularly with reference to two speciflc embodiments, it is to be-understood that various changes and modifications may be made in the structure shown without departing from the invention and the latter is therefore to be limited only as set forth in the appended claims.

I claim:

1. In a multiple barrel pump comprising a series of parallel pump barrels concentrically posi- 7 5 tioned about a central axis, plungers operating in said barrels, a spindle, means for pivotally supporting one end of said spindle in alignment with said central axis whereby the other end of the spindle is free to gyrate about said axis, lever means on said spindle extending radially from the pivot point of said spindle into alignment withsaid barrels, means linking each of said plungers to the juxtaposed portion of said lever means whereby gyration of said spindle reciprocates said plunger, in said barrels, means for gyrating said spindle comprising a member rotatably supported adjacent the other end of said spindle for rotation about said central axis, guide means on said member extending diametrically with respect thereto for slidably engaging said other end of said spindle, means for continuously rotating said member, stroke-varying means on said member for moving said other end of said" spindle diametrically in said guide means to vary the inclination of, and are of gyration of said spindle while said memberis rotating, and stationary control means constantly coupled to said stroke-varying means for moving the latter while said member is rotating.

2. A pump as described in claim 1 in which .said stroke-varying means comprises hydraulic motor means responsive to fluid pressure to increase the inclination of said spindle from said central axis, and in which said control means includes means for constantly supplying fluid under predetermined pressure to said hydraulic motor means.

3. A pump as described in claim 1 in which said strokevarying means comprises hydraulic motor means responsive to fluid pressure to in crease the inclination of said spindle from said central axis, in which some of said pump barrels and associated plungers constitute working pumps and others constitute control pumps for supplying fluid under pressure to said hydraulic motor means and in which said control means comprises a valve for limiting the pressured fluid applied to said hydraulic motor means to a predetermined value.

4. A pump as described in claim 1 in which said levermeans on said spindle comprises a disc projecting from the spindle into the projected paths of travel of said plungers, and in which each 01 said linking means comprises a yoke straddling the edge '01 said disc and'connected to its associated plunger on one side of said disc with a guide rod aligned with the plunger and connected to said yoke on the other side oi said disc, and a guide for each rod.

5. A pump as described in claim 1 in which said stroke-varying means comprises hydraulic motor means responsive to fluid pressure to increase the inclination of said spindle from said central axis, in which some of said pumpbarrels and associated plungers constitute'working pumps and others constitute control pumps for supplying fluid under pressure to said hydraulic motor means, said control pumps being uniformly circumferentially spaced about said axis and each positioned between a pair of working pumps, and means for limiting the pressure of fluid applied from said control pumps to said hydraulic motor means to a predetermined value.

6. In a pump of the type described, a casing, a spindle within. said casing pivotally supported at its lower end from said casing, whereby the upper end is free to gyrate about a vertical axis extending through the pivot point, means for gy- 5 rating said spindle, fluid actuating means for radially shifting the upper end of said spindle away from said axis to increase the arc of gyration on said spindle, a wobble disc on said spindle, extending radially therefrom, a plurality of control pumps, each comprising a-barrel and a plunger symmetrically positioned about said axis and above said wobble disc, means linking said control pump plungers to said wobble disc, said control pumps having suction ports communicating with the interior of said casing and discharge ports communicating with said fluid-actuated means, means for regulating the pressure of fluid applied to said fluid-actuated means, means tor discharging excess fluid from said control pump discharge ports back into said casing, a plurality of working pumps each comprising a barrel and plunger detachably supported exterior of and below said casing, and push rods extending through packing glands in said casing for coupling said working pump plungers to said wobble plate.

,7. A pump as described in claim 1 in which said stroke-varying means for moving said other end of said spindle diametrically in said guide means comprises a pair of cylinders positioned parallel to and on opposite sides of said guide means,

'plungers in said cylinders, a yoke connecting said two plungers adapted to contact'said spindle, and

means for supplying fluid under predetermined pressure to said cylinders. a 8. In a pump of the type described, a casing,

a spindle within said casing pivotally supported at one end from said casingiwhereby the other end is free to gyrate about a central axis extend- 40 dle through a stroke proportional to the radius of gyration of the spindle, some of said pumps constitutingcontrol pumps and others constituting working pumps, fluid responsivemeans supplied with fluid from said control pumps for urging said spindle away from said central axis to increase the stroke of said pump,--and spring means for constantly urging said spindle into inclined position out of alignment with said central axis, said spring means being relatively weak,

whereby it exerts a force on said spindle substantially negligible in comparison with the reactive force on said spindle exerted by said pump plungers, whereby the arc of gyration of said 55 spindle is controlled substantially entirely by the relative pressures developed by said control pumps respectively.

and working pumps,

1 DAVID MITCBELL, Ja- 

